Well it's more like neutralizing as opposed to filtering, and sure there probably are some aimed at people with central air that want to reduce VOCs. I believe I've seen standalone filters in the context of plant growing. And perhaps there are carbon aquarium filters that would work for DIY? I myself just went for some off the shelf air "purifiers", which have a prefilter + particulate filter + carbon filter stack. It's the path of overpaying for a fan and gimmicky replacements, but they're quiet, automatically ramp up speed for high VOCs, and didn't require me to DIY something for once.